Earlier quoted context omitted.
Many of the more esoteric conspiracy theories are hard to debunk. Lets take the earth if round, prove it. You can bring up many cases, sails disappearing behind the horizon, goemetry, etc. but actually doing these measurements and calculations cold is pretty hard. And whenever you bring up a fact, they will dismiss it out of hand. Tectonic plates, I believe they exist, I have seen the evidence in books. But I doubt I…
You don't particularly need calculations, just have friends around the world or even a couple hundred miles away, get on a video call to prove the world is round. Whatever your pet theory of how the sun moves across the "flat" earth can be contradicted with a couple of facetime calls.
It doesn’t really matter if the earth is flat or not, for them it’s about being part of a community of people who believe in something that society tells them is wrong. There is no changing minds besides the 1 in a million you hear about and so all the calculations you could do would never work, sadly.